Stability of Alumina Catalyst Support in Supercritical Water for Hydrogen Production

Reforming in supercritical water to produce high pressure hydrogen is emerging as a promising technology. Experiments have shown that ruthenium catalyst on gamma-Al2O3 support can effectively catalyze the reaction [Byrd et al., Hydrogen production from glycerol by reforming in supercritical water over Ru/Al2O3 catalyst. Fuel (2008), 87, 2956-2960]. However, gamma form of alumina can interact with supercritical water to transfer into alpha form of alumina. In this work, the stability of ruthenium catalysts supported on gamma-alumina and cerium-modified alumina in supercritical water has been studied with the objective of determining cerium's ability to stabilize the gamma- to alpha- alumina phase transition in the supercritical water environment. Supported ruthenium catalysts with cerium loadings of 0 to 10 wt% were evaluated both after calcination and after subsequent reduction treatments and characterized by the Brunauer-Emmett-Teller method, X-ray diffraction, transmission electron microscopy, inductively coupled plasma mass spectroscopy, and UV-VIS diffuse reflectance spectroscopy.